151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski/* 251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * Copyright (c) 1999, 2008, Oracle and/or its affiliates. All rights reserved. 351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * This code is free software; you can redistribute it and/or modify it 651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * under the terms of the GNU General Public License version 2 only, as 751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * published by the Free Software Foundation. Oracle designates this 851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * particular file as subject to the "Classpath" exception as provided 951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * by Oracle in the LICENSE file that accompanied this code. 1051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 1151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * This code is distributed in the hope that it will be useful, but WITHOUT 1251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 1351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 1451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * version 2 for more details (a copy is included in the LICENSE file that 1551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * accompanied this code). 1651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 1751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * You should have received a copy of the GNU General Public License version 1851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 2 along with this work; if not, write to the Free Software Foundation, 1951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 2051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 2151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 2251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * or visit www.oracle.com if you need additional information or have any 2351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * questions. 2451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 2551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 2651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebskipackage java.util; 2751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebskiimport java.util.Date; 2851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebskiimport java.util.concurrent.atomic.AtomicInteger; 2951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 3051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski/** 3151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * A facility for threads to schedule tasks for future execution in a 3251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * background thread. Tasks may be scheduled for one-time execution, or for 3351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * repeated execution at regular intervals. 3451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 3551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p>Corresponding to each <tt>Timer</tt> object is a single background 3651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * thread that is used to execute all of the timer's tasks, sequentially. 3751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * Timer tasks should complete quickly. If a timer task takes excessive time 3851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * to complete, it "hogs" the timer's task execution thread. This can, in 3951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * turn, delay the execution of subsequent tasks, which may "bunch up" and 4051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * execute in rapid succession when (and if) the offending task finally 4151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * completes. 4251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 4351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p>After the last live reference to a <tt>Timer</tt> object goes away 4451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <i>and</i> all outstanding tasks have completed execution, the timer's task 4551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * execution thread terminates gracefully (and becomes subject to garbage 4651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * collection). However, this can take arbitrarily long to occur. By 4751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * default, the task execution thread does not run as a <i>daemon thread</i>, 4851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * so it is capable of keeping an application from terminating. If a caller 4951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * wants to terminate a timer's task execution thread rapidly, the caller 5051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * should invoke the timer's <tt>cancel</tt> method. 5151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 5251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p>If the timer's task execution thread terminates unexpectedly, for 5351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * example, because its <tt>stop</tt> method is invoked, any further 5451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * attempt to schedule a task on the timer will result in an 5551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <tt>IllegalStateException</tt>, as if the timer's <tt>cancel</tt> 5651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * method had been invoked. 5751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 5851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p>This class is thread-safe: multiple threads can share a single 5951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <tt>Timer</tt> object without the need for external synchronization. 6051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 6151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p>This class does <i>not</i> offer real-time guarantees: it schedules 6251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * tasks using the <tt>Object.wait(long)</tt> method. 6351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 6451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p>Java 5.0 introduced the {@code java.util.concurrent} package and 6551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * one of the concurrency utilities therein is the {@link 6651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * java.util.concurrent.ScheduledThreadPoolExecutor 6751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * ScheduledThreadPoolExecutor} which is a thread pool for repeatedly 6851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * executing tasks at a given rate or delay. It is effectively a more 6951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * versatile replacement for the {@code Timer}/{@code TimerTask} 7051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * combination, as it allows multiple service threads, accepts various 7151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * time units, and doesn't require subclassing {@code TimerTask} (just 7251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * implement {@code Runnable}). Configuring {@code 7351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * ScheduledThreadPoolExecutor} with one thread makes it equivalent to 7451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * {@code Timer}. 7551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 7651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p>Implementation note: This class scales to large numbers of concurrently 7751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * scheduled tasks (thousands should present no problem). Internally, 7851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * it uses a binary heap to represent its task queue, so the cost to schedule 7951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * a task is O(log n), where n is the number of concurrently scheduled tasks. 8051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 8151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p>Implementation note: All constructors start a timer thread. 8251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 8351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @author Josh Bloch 8451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @see TimerTask 8551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @see Object#wait(long) 8651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @since 1.3 8751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 8851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 8951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebskipublic class Timer { 9051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski /** 9151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * The timer task queue. This data structure is shared with the timer 9251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * thread. The timer produces tasks, via its various schedule calls, 9351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * and the timer thread consumes, executing timer tasks as appropriate, 9451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * and removing them from the queue when they're obsolete. 9551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 9651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski private final TaskQueue queue = new TaskQueue(); 9751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 9851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski /** 9951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * The timer thread. 10051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 10151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski private final TimerThread thread = new TimerThread(queue); 10251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 10351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski /** 10451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * This object causes the timer's task execution thread to exit 10551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * gracefully when there are no live references to the Timer object and no 10651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * tasks in the timer queue. It is used in preference to a finalizer on 10751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * Timer as such a finalizer would be susceptible to a subclass's 10851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * finalizer forgetting to call it. 10951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 11051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski private final Object threadReaper = new Object() { 11151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski protected void finalize() throws Throwable { 11251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski synchronized(queue) { 11351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski thread.newTasksMayBeScheduled = false; 11451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski queue.notify(); // In case queue is empty. 11551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski } 11651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski } 11751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski }; 11851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 11951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski /** 12051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * This ID is used to generate thread names. 12151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 12251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski private final static AtomicInteger nextSerialNumber = new AtomicInteger(0); 12351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski private static int serialNumber() { 12451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski return nextSerialNumber.getAndIncrement(); 12551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski } 12651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 12751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski /** 12851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * Creates a new timer. The associated thread does <i>not</i> 12951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * {@linkplain Thread#setDaemon run as a daemon}. 13051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 13151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski public Timer() { 13251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski this("Timer-" + serialNumber()); 13351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski } 13451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 13551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski /** 13651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * Creates a new timer whose associated thread may be specified to 13751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * {@linkplain Thread#setDaemon run as a daemon}. 13851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * A daemon thread is called for if the timer will be used to 13951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * schedule repeating "maintenance activities", which must be 14051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * performed as long as the application is running, but should not 14151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * prolong the lifetime of the application. 14251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 14351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @param isDaemon true if the associated thread should run as a daemon. 14451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 14551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski public Timer(boolean isDaemon) { 14651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski this("Timer-" + serialNumber(), isDaemon); 14751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski } 14851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 14951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski /** 15051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * Creates a new timer whose associated thread has the specified name. 15151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * The associated thread does <i>not</i> 15251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * {@linkplain Thread#setDaemon run as a daemon}. 15351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 15451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @param name the name of the associated thread 15551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @throws NullPointerException if {@code name} is null 15651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @since 1.5 15751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 15851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski public Timer(String name) { 15951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski thread.setName(name); 16051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski thread.start(); 16151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski } 16251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 16351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski /** 16451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * Creates a new timer whose associated thread has the specified name, 16551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * and may be specified to 16651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * {@linkplain Thread#setDaemon run as a daemon}. 16751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 16851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @param name the name of the associated thread 16951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @param isDaemon true if the associated thread should run as a daemon 17051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @throws NullPointerException if {@code name} is null 17151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @since 1.5 17251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 17351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski public Timer(String name, boolean isDaemon) { 17451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski thread.setName(name); 17551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski thread.setDaemon(isDaemon); 17651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski thread.start(); 17751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski } 17851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 17951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski /** 18051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * Schedules the specified task for execution after the specified delay. 18151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 18251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @param task task to be scheduled. 18351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @param delay delay in milliseconds before task is to be executed. 18451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @throws IllegalArgumentException if <tt>delay</tt> is negative, or 18551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <tt>delay + System.currentTimeMillis()</tt> is negative. 18651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @throws IllegalStateException if task was already scheduled or 18751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * cancelled, timer was cancelled, or timer thread terminated. 18851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @throws NullPointerException if {@code task} is null 18951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 19051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski public void schedule(TimerTask task, long delay) { 19151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski if (delay < 0) 19251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski throw new IllegalArgumentException("Negative delay."); 19351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski sched(task, System.currentTimeMillis()+delay, 0); 19451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski } 19551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 19651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski /** 19751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * Schedules the specified task for execution at the specified time. If 19851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * the time is in the past, the task is scheduled for immediate execution. 19951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 20051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @param task task to be scheduled. 20151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @param time time at which task is to be executed. 20251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @throws IllegalArgumentException if <tt>time.getTime()</tt> is negative. 20351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @throws IllegalStateException if task was already scheduled or 20451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * cancelled, timer was cancelled, or timer thread terminated. 20551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @throws NullPointerException if {@code task} or {@code time} is null 20651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 20751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski public void schedule(TimerTask task, Date time) { 20851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski sched(task, time.getTime(), 0); 20951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski } 21051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 21151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski /** 21251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * Schedules the specified task for repeated <i>fixed-delay execution</i>, 21351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * beginning after the specified delay. Subsequent executions take place 21451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * at approximately regular intervals separated by the specified period. 21551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 21651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p>In fixed-delay execution, each execution is scheduled relative to 21751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * the actual execution time of the previous execution. If an execution 21851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * is delayed for any reason (such as garbage collection or other 21951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * background activity), subsequent executions will be delayed as well. 22051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * In the long run, the frequency of execution will generally be slightly 22151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * lower than the reciprocal of the specified period (assuming the system 22251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * clock underlying <tt>Object.wait(long)</tt> is accurate). 22351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 22451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p>Fixed-delay execution is appropriate for recurring activities 22551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * that require "smoothness." In other words, it is appropriate for 22651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * activities where it is more important to keep the frequency accurate 22751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * in the short run than in the long run. This includes most animation 22851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * tasks, such as blinking a cursor at regular intervals. It also includes 22951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * tasks wherein regular activity is performed in response to human 23051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * input, such as automatically repeating a character as long as a key 23151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * is held down. 23251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 23351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @param task task to be scheduled. 23451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @param delay delay in milliseconds before task is to be executed. 23551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @param period time in milliseconds between successive task executions. 23651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @throws IllegalArgumentException if {@code delay < 0}, or 23751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * {@code delay + System.currentTimeMillis() < 0}, or 23851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * {@code period <= 0} 23951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @throws IllegalStateException if task was already scheduled or 24051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * cancelled, timer was cancelled, or timer thread terminated. 24151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @throws NullPointerException if {@code task} is null 24251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 24351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski public void schedule(TimerTask task, long delay, long period) { 24451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski if (delay < 0) 24551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski throw new IllegalArgumentException("Negative delay."); 24651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski if (period <= 0) 24751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski throw new IllegalArgumentException("Non-positive period."); 24851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski sched(task, System.currentTimeMillis()+delay, -period); 24951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski } 25051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 25151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski /** 25251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * Schedules the specified task for repeated <i>fixed-delay execution</i>, 25351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * beginning at the specified time. Subsequent executions take place at 25451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * approximately regular intervals, separated by the specified period. 25551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 25651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p>In fixed-delay execution, each execution is scheduled relative to 25751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * the actual execution time of the previous execution. If an execution 25851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * is delayed for any reason (such as garbage collection or other 25951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * background activity), subsequent executions will be delayed as well. 26051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * In the long run, the frequency of execution will generally be slightly 26151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * lower than the reciprocal of the specified period (assuming the system 26251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * clock underlying <tt>Object.wait(long)</tt> is accurate). As a 26351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * consequence of the above, if the scheduled first time is in the past, 26451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * it is scheduled for immediate execution. 26551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 26651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p>Fixed-delay execution is appropriate for recurring activities 26751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * that require "smoothness." In other words, it is appropriate for 26851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * activities where it is more important to keep the frequency accurate 26951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * in the short run than in the long run. This includes most animation 27051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * tasks, such as blinking a cursor at regular intervals. It also includes 27151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * tasks wherein regular activity is performed in response to human 27251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * input, such as automatically repeating a character as long as a key 27351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * is held down. 27451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 27551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @param task task to be scheduled. 27651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @param firstTime First time at which task is to be executed. 27751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @param period time in milliseconds between successive task executions. 27851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @throws IllegalArgumentException if {@code firstTime.getTime() < 0}, or 27951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * {@code period <= 0} 28051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @throws IllegalStateException if task was already scheduled or 28151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * cancelled, timer was cancelled, or timer thread terminated. 28251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @throws NullPointerException if {@code task} or {@code firstTime} is null 28351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 28451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski public void schedule(TimerTask task, Date firstTime, long period) { 28551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski if (period <= 0) 28651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski throw new IllegalArgumentException("Non-positive period."); 28751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski sched(task, firstTime.getTime(), -period); 28851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski } 28951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 29051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski /** 29151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * Schedules the specified task for repeated <i>fixed-rate execution</i>, 29251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * beginning after the specified delay. Subsequent executions take place 29351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * at approximately regular intervals, separated by the specified period. 29451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 29551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p>In fixed-rate execution, each execution is scheduled relative to the 29651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * scheduled execution time of the initial execution. If an execution is 29751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * delayed for any reason (such as garbage collection or other background 29851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * activity), two or more executions will occur in rapid succession to 29951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * "catch up." In the long run, the frequency of execution will be 30051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * exactly the reciprocal of the specified period (assuming the system 30151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * clock underlying <tt>Object.wait(long)</tt> is accurate). 30251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 30351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p>Fixed-rate execution is appropriate for recurring activities that 30451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * are sensitive to <i>absolute</i> time, such as ringing a chime every 30551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * hour on the hour, or running scheduled maintenance every day at a 30651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * particular time. It is also appropriate for recurring activities 30751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * where the total time to perform a fixed number of executions is 30851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * important, such as a countdown timer that ticks once every second for 30951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * ten seconds. Finally, fixed-rate execution is appropriate for 31051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * scheduling multiple repeating timer tasks that must remain synchronized 31151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * with respect to one another. 31251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 31351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @param task task to be scheduled. 31451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @param delay delay in milliseconds before task is to be executed. 31551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @param period time in milliseconds between successive task executions. 31651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @throws IllegalArgumentException if {@code delay < 0}, or 31751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * {@code delay + System.currentTimeMillis() < 0}, or 31851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * {@code period <= 0} 31951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @throws IllegalStateException if task was already scheduled or 32051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * cancelled, timer was cancelled, or timer thread terminated. 32151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @throws NullPointerException if {@code task} is null 32251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 32351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski public void scheduleAtFixedRate(TimerTask task, long delay, long period) { 32451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski if (delay < 0) 32551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski throw new IllegalArgumentException("Negative delay."); 32651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski if (period <= 0) 32751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski throw new IllegalArgumentException("Non-positive period."); 32851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski sched(task, System.currentTimeMillis()+delay, period); 32951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski } 33051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 33151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski /** 33251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * Schedules the specified task for repeated <i>fixed-rate execution</i>, 33351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * beginning at the specified time. Subsequent executions take place at 33451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * approximately regular intervals, separated by the specified period. 33551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 33651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p>In fixed-rate execution, each execution is scheduled relative to the 33751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * scheduled execution time of the initial execution. If an execution is 33851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * delayed for any reason (such as garbage collection or other background 33951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * activity), two or more executions will occur in rapid succession to 34051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * "catch up." In the long run, the frequency of execution will be 34151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * exactly the reciprocal of the specified period (assuming the system 34251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * clock underlying <tt>Object.wait(long)</tt> is accurate). As a 34351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * consequence of the above, if the scheduled first time is in the past, 34451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * then any "missed" executions will be scheduled for immediate "catch up" 34551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * execution. 34651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 34751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p>Fixed-rate execution is appropriate for recurring activities that 34851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * are sensitive to <i>absolute</i> time, such as ringing a chime every 34951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * hour on the hour, or running scheduled maintenance every day at a 35051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * particular time. It is also appropriate for recurring activities 35151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * where the total time to perform a fixed number of executions is 35251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * important, such as a countdown timer that ticks once every second for 35351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * ten seconds. Finally, fixed-rate execution is appropriate for 35451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * scheduling multiple repeating timer tasks that must remain synchronized 35551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * with respect to one another. 35651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 35751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @param task task to be scheduled. 35851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @param firstTime First time at which task is to be executed. 35951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @param period time in milliseconds between successive task executions. 36051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @throws IllegalArgumentException if {@code firstTime.getTime() < 0} or 36151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * {@code period <= 0} 36251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @throws IllegalStateException if task was already scheduled or 36351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * cancelled, timer was cancelled, or timer thread terminated. 36451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @throws NullPointerException if {@code task} or {@code firstTime} is null 36551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 36651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski public void scheduleAtFixedRate(TimerTask task, Date firstTime, 36751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski long period) { 36851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski if (period <= 0) 36951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski throw new IllegalArgumentException("Non-positive period."); 37051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski sched(task, firstTime.getTime(), period); 37151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski } 37251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 37351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski /** 37451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * Schedule the specified timer task for execution at the specified 37551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * time with the specified period, in milliseconds. If period is 37651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * positive, the task is scheduled for repeated execution; if period is 37751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * zero, the task is scheduled for one-time execution. Time is specified 37851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * in Date.getTime() format. This method checks timer state, task state, 37951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * and initial execution time, but not period. 38051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 38151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @throws IllegalArgumentException if <tt>time</tt> is negative. 38251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @throws IllegalStateException if task was already scheduled or 38351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * cancelled, timer was cancelled, or timer thread terminated. 38451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @throws NullPointerException if {@code task} is null 38551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 38651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski private void sched(TimerTask task, long time, long period) { 38751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski if (time < 0) 38851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski throw new IllegalArgumentException("Illegal execution time."); 38951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 39051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski // Constrain value of period sufficiently to prevent numeric 39151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski // overflow while still being effectively infinitely large. 39251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski if (Math.abs(period) > (Long.MAX_VALUE >> 1)) 39351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski period >>= 1; 39451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 39551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski synchronized(queue) { 39651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski if (!thread.newTasksMayBeScheduled) 39751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski throw new IllegalStateException("Timer already cancelled."); 39851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 39951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski synchronized(task.lock) { 40051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski if (task.state != TimerTask.VIRGIN) 40151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski throw new IllegalStateException( 40251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski "Task already scheduled or cancelled"); 40351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski task.nextExecutionTime = time; 40451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski task.period = period; 40551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski task.state = TimerTask.SCHEDULED; 40651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski } 40751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 40851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski queue.add(task); 40951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski if (queue.getMin() == task) 41051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski queue.notify(); 41151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski } 41251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski } 41351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 41451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski /** 41551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * Terminates this timer, discarding any currently scheduled tasks. 41651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * Does not interfere with a currently executing task (if it exists). 41751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * Once a timer has been terminated, its execution thread terminates 41851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * gracefully, and no more tasks may be scheduled on it. 41951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 42051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p>Note that calling this method from within the run method of a 42151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * timer task that was invoked by this timer absolutely guarantees that 42251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * the ongoing task execution is the last task execution that will ever 42351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * be performed by this timer. 42451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 42551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p>This method may be called repeatedly; the second and subsequent 42651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * calls have no effect. 42751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 42851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski public void cancel() { 42951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski synchronized(queue) { 43051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski thread.newTasksMayBeScheduled = false; 43151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski queue.clear(); 43251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski queue.notify(); // In case queue was already empty. 43351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski } 43451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski } 43551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 43651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski /** 43751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * Removes all cancelled tasks from this timer's task queue. <i>Calling 43851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * this method has no effect on the behavior of the timer</i>, but 43951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * eliminates the references to the cancelled tasks from the queue. 44051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * If there are no external references to these tasks, they become 44151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * eligible for garbage collection. 44251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 44351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p>Most programs will have no need to call this method. 44451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * It is designed for use by the rare application that cancels a large 44551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * number of tasks. Calling this method trades time for space: the 44651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * runtime of the method may be proportional to n + c log n, where n 44751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * is the number of tasks in the queue and c is the number of cancelled 44851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * tasks. 44951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 45051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p>Note that it is permissible to call this method from within a 45151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * a task scheduled on this timer. 45251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 45351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @return the number of tasks removed from the queue. 45451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @since 1.5 45551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 45651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski public int purge() { 45751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski int result = 0; 45851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 45951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski synchronized(queue) { 46051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski for (int i = queue.size(); i > 0; i--) { 46151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski if (queue.get(i).state == TimerTask.CANCELLED) { 46251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski queue.quickRemove(i); 46351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski result++; 46451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski } 46551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski } 46651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 46751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski if (result != 0) 46851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski queue.heapify(); 46951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski } 47051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 47151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski return result; 47251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski } 47351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski} 47451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 47551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski/** 47651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * This "helper class" implements the timer's task execution thread, which 47751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * waits for tasks on the timer queue, executions them when they fire, 47851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * reschedules repeating tasks, and removes cancelled tasks and spent 47951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * non-repeating tasks from the queue. 48051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 48151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebskiclass TimerThread extends Thread { 48251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski /** 48351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * This flag is set to false by the reaper to inform us that there 48451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * are no more live references to our Timer object. Once this flag 48551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * is true and there are no more tasks in our queue, there is no 48651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * work left for us to do, so we terminate gracefully. Note that 48751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * this field is protected by queue's monitor! 48851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 48951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski boolean newTasksMayBeScheduled = true; 49051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 49151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski /** 49251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * Our Timer's queue. We store this reference in preference to 49351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * a reference to the Timer so the reference graph remains acyclic. 49451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * Otherwise, the Timer would never be garbage-collected and this 49551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * thread would never go away. 49651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 49751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski private TaskQueue queue; 49851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 49951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski TimerThread(TaskQueue queue) { 50051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski this.queue = queue; 50151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski } 50251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 50351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski public void run() { 50451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski try { 50551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski mainLoop(); 50651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski } finally { 50751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski // Someone killed this Thread, behave as if Timer cancelled 50851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski synchronized(queue) { 50951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski newTasksMayBeScheduled = false; 51051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski queue.clear(); // Eliminate obsolete references 51151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski } 51251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski } 51351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski } 51451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 51551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski /** 51651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * The main timer loop. (See class comment.) 51751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 51851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski private void mainLoop() { 51951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski while (true) { 52051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski try { 52151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski TimerTask task; 52251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski boolean taskFired; 52351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski synchronized(queue) { 52451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski // Wait for queue to become non-empty 52551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski while (queue.isEmpty() && newTasksMayBeScheduled) 52651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski queue.wait(); 52751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski if (queue.isEmpty()) 52851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski break; // Queue is empty and will forever remain; die 52951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 53051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski // Queue nonempty; look at first evt and do the right thing 53151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski long currentTime, executionTime; 53251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski task = queue.getMin(); 53351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski synchronized(task.lock) { 53451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski if (task.state == TimerTask.CANCELLED) { 53551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski queue.removeMin(); 53651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski continue; // No action required, poll queue again 53751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski } 53851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski currentTime = System.currentTimeMillis(); 53951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski executionTime = task.nextExecutionTime; 54051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski if (taskFired = (executionTime<=currentTime)) { 54151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski if (task.period == 0) { // Non-repeating, remove 54251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski queue.removeMin(); 54351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski task.state = TimerTask.EXECUTED; 54451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski } else { // Repeating task, reschedule 54551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski queue.rescheduleMin( 54651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski task.period<0 ? currentTime - task.period 54751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski : executionTime + task.period); 54851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski } 54951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski } 55051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski } 55151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski if (!taskFired) // Task hasn't yet fired; wait 55251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski queue.wait(executionTime - currentTime); 55351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski } 55451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski if (taskFired) // Task fired; run it, holding no locks 55551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski task.run(); 55651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski } catch(InterruptedException e) { 55751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski } 55851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski } 55951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski } 56051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski} 56151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 56251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski/** 56351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * This class represents a timer task queue: a priority queue of TimerTasks, 56451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * ordered on nextExecutionTime. Each Timer object has one of these, which it 56551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * shares with its TimerThread. Internally this class uses a heap, which 56651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * offers log(n) performance for the add, removeMin and rescheduleMin 56751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * operations, and constant time performance for the getMin operation. 56851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 56951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebskiclass TaskQueue { 57051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski /** 57151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * Priority queue represented as a balanced binary heap: the two children 57251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * of queue[n] are queue[2*n] and queue[2*n+1]. The priority queue is 57351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * ordered on the nextExecutionTime field: The TimerTask with the lowest 57451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * nextExecutionTime is in queue[1] (assuming the queue is nonempty). For 57551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * each node n in the heap, and each descendant of n, d, 57651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * n.nextExecutionTime <= d.nextExecutionTime. 57751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 57851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski private TimerTask[] queue = new TimerTask[128]; 57951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 58051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski /** 58151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * The number of tasks in the priority queue. (The tasks are stored in 58251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * queue[1] up to queue[size]). 58351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 58451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski private int size = 0; 58551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 58651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski /** 58751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * Returns the number of tasks currently on the queue. 58851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 58951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski int size() { 59051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski return size; 59151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski } 59251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 59351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski /** 59451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * Adds a new task to the priority queue. 59551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 59651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski void add(TimerTask task) { 59751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski // Grow backing store if necessary 59851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski if (size + 1 == queue.length) 59951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski queue = Arrays.copyOf(queue, 2*queue.length); 60051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 60151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski queue[++size] = task; 60251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski fixUp(size); 60351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski } 60451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 60551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski /** 60651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * Return the "head task" of the priority queue. (The head task is an 60751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * task with the lowest nextExecutionTime.) 60851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 60951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski TimerTask getMin() { 61051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski return queue[1]; 61151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski } 61251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 61351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski /** 61451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * Return the ith task in the priority queue, where i ranges from 1 (the 61551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * head task, which is returned by getMin) to the number of tasks on the 61651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * queue, inclusive. 61751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 61851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski TimerTask get(int i) { 61951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski return queue[i]; 62051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski } 62151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 62251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski /** 62351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * Remove the head task from the priority queue. 62451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 62551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski void removeMin() { 62651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski queue[1] = queue[size]; 62751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski queue[size--] = null; // Drop extra reference to prevent memory leak 62851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski fixDown(1); 62951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski } 63051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 63151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski /** 63251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * Removes the ith element from queue without regard for maintaining 63351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * the heap invariant. Recall that queue is one-based, so 63451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 1 <= i <= size. 63551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 63651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski void quickRemove(int i) { 63751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski assert i <= size; 63851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 63951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski queue[i] = queue[size]; 64051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski queue[size--] = null; // Drop extra ref to prevent memory leak 64151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski } 64251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 64351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski /** 64451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * Sets the nextExecutionTime associated with the head task to the 64551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * specified value, and adjusts priority queue accordingly. 64651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 64751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski void rescheduleMin(long newTime) { 64851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski queue[1].nextExecutionTime = newTime; 64951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski fixDown(1); 65051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski } 65151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 65251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski /** 65351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * Returns true if the priority queue contains no elements. 65451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 65551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski boolean isEmpty() { 65651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski return size==0; 65751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski } 65851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 65951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski /** 66051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * Removes all elements from the priority queue. 66151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 66251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski void clear() { 66351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski // Null out task references to prevent memory leak 66451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski for (int i=1; i<=size; i++) 66551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski queue[i] = null; 66651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 66751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski size = 0; 66851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski } 66951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 67051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski /** 67151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * Establishes the heap invariant (described above) assuming the heap 67251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * satisfies the invariant except possibly for the leaf-node indexed by k 67351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * (which may have a nextExecutionTime less than its parent's). 67451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 67551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * This method functions by "promoting" queue[k] up the hierarchy 67651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * (by swapping it with its parent) repeatedly until queue[k]'s 67751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * nextExecutionTime is greater than or equal to that of its parent. 67851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 67951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski private void fixUp(int k) { 68051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski while (k > 1) { 68151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski int j = k >> 1; 68251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski if (queue[j].nextExecutionTime <= queue[k].nextExecutionTime) 68351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski break; 68451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski TimerTask tmp = queue[j]; queue[j] = queue[k]; queue[k] = tmp; 68551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski k = j; 68651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski } 68751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski } 68851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 68951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski /** 69051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * Establishes the heap invariant (described above) in the subtree 69151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * rooted at k, which is assumed to satisfy the heap invariant except 69251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * possibly for node k itself (which may have a nextExecutionTime greater 69351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * than its children's). 69451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 69551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * This method functions by "demoting" queue[k] down the hierarchy 69651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * (by swapping it with its smaller child) repeatedly until queue[k]'s 69751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * nextExecutionTime is less than or equal to those of its children. 69851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 69951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski private void fixDown(int k) { 70051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski int j; 70151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski while ((j = k << 1) <= size && j > 0) { 70251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski if (j < size && 70351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski queue[j].nextExecutionTime > queue[j+1].nextExecutionTime) 70451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski j++; // j indexes smallest kid 70551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski if (queue[k].nextExecutionTime <= queue[j].nextExecutionTime) 70651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski break; 70751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski TimerTask tmp = queue[j]; queue[j] = queue[k]; queue[k] = tmp; 70851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski k = j; 70951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski } 71051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski } 71151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 71251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski /** 71351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * Establishes the heap invariant (described above) in the entire tree, 71451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * assuming nothing about the order of the elements prior to the call. 71551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 71651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski void heapify() { 71751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski for (int i = size/2; i >= 1; i--) 71851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski fixDown(i); 71951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski } 72051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski} 721